Gas burners

ABSTRACT

A pressure-fed gas burner has a gas/air mixer assembly comprising a venturi plate, with a ring of axial venturi ports, and a coaxial flame-retention plate together defining an annular mixture chamber into which the venturi ports open and from which a peripheral outlet delivers the gas/air mixture to a combustion chamber.

3 United States Patent Kirk et al.

[ Oct. 28, 1975 GAS BURNERS Inventors: Harold W. E. Kirk, Evesham; Robert D. Thomas, Stourport-on-Severn, both of England Assignee: Morganite Thermal Designs Ltd.,

Norton, England Filed: Sept. 12, 1974 Appl. No.: 505,5 16

Foreign Application Priority Data Jan. 4, 1974 United Kingdom 442/74 U.S. Cl. 431/350; 431/158; 239/427.3;

239/434 Int. Cl. F23D 13/24 Field of Search 431/158, 350, 351, 353,

[56] References Cited UNITED STATES PATENTS 706,633 8/1902 Beler 431/350 2,407,188 9/1946 Sutton l .1 431/350 2,870,829 l/1959 Williams 431/350 FOREIGN PATENTS OR APPLICATIONS 224,911 7/1925 United Kingdom 239/431 Primary Examiner-Carroll B. Dority, Jr. Attorney, Agent, 0r'FirmLarson, Taylor & Hinds 57 7 ABSTRACT A pressure-fed gas burner has a gas/air mixer assembly comprising a venturi plate, with a ring of axial venturi ports, and a coaxial flame-retention plate together defining an annular mixture chamber into which the venturi ports open and from which a peripheral outlet delivers the gas/air mixture to a combustion chamber.

12 Claims, 1 Drawing Figure US. Patent Oct. 28, 1975 3,915,624

GAS BURNERS SUBJECT AND OBJECT OF THE INVENTION This invention relates to gas burners and aims at providing a burner of compact construction, with provision for substitution or replacement of parts,'quietness of operation and good control.

BACKGROUND AND PRIOR ART The kind of burner with which the invention is primarily concerned is designed to be supplied with air under pressure to a venturi so as to entrain gas for mixing with the air for burning in a combustion chamber. The invention will be described as applied to such a burner but it is also applicable to a burner in which gas under pressure is used to entrain air. A burner of either kind will be referred to as a pressure-fed burner.

STATEMENT OF THE INVENTION AND PREFERRED FEATURES According to the invention, in or for a pressure-fed burner, a mixer assembly comprises a venturi plate having at least one ring of axial venturi ports and, coaxial therewith, a flame-retention plate which defines be tween itself and the venturi plate an annular mixture chamber into which venturi ports open and which has a peripheral outlet for delivery of a gas/air mixture to a combustion chamber.

In a preferred construction, the annular chamber and its peripheral outlet are both defined, against a plane face of the venturi plate, by an annular recess in a face of the flame-retention plate, the recess being formed between a central boss, which abuts against the venturi plate, and a surrounding rim flange, of less axial height than the boss, which leaves a clearance between itself and the venturi plate to define the peripheral outlet.

The venturi plate may have an inner ring and an outer ring of venturi ports but preferably its rim is designed to form the inner wall of an annular venturi passage.

A burner according to the invention includes a mixer assembly, as described above, mounted coaxially in a nozzle assembly comprising a nozzle back plate, with an inner ring of jets directed into the venturi ports and an outer ring of jets directed axially at or past the pe riphery of the venturi plate, and a nozzle front plate which has a central opening defining a combustion chamber which extends around the peripheral outlet from the mixer assembly and downstream from the periphery of the venturi plate.

In a preferred construction, the periphery of the venturi plate has a plain circular rim which defines, between itself and the surrounding wall of the nozzle front plate opening, an annular venturi passage in axial alignment with the outer ring of jets in the nozzle back plate. The venturi plate rim could however have a ring of axial venturi slots or ports respectively in axial align ment with the outer jets of the nozzle back plate.

The inner ring of jets in the nozzle back plate are preferably designed as metered pilot jets removably mounted in screw-threaded bores so that they can be selected and replaced to suit size or fuel requirements.

The outer ring of jets serve as main jets and conveniently are simply metered bores. The size, or capacity. of the burner is determined by the number of outer ring jets, fine selection being afforded by using more or less of a large number, e.g. or more, of small jets. The flow rate also depends upon the total cross-sectional venturi area and this can be determined mainly by the radial clearance between the rim of the venturi plate and the wall of the front nozzle plate opening.

DESCRIPTION OF PREFERRED EMBODIMENT The invention is illustrated by way of example on the accompanying drawing which shows, in axial section, a burner in accordance with the invention mounted on the end of a gas-supply pipe in an elbow terminal of a pressure-air supply pipe.

As shown by the drawing, the end of a gas pipe I is screw-threaded for the mounting thereon of a back nozzle plate 2 which has an inner ring of removable air jets 3 and an outer ring of air jet bores 4.

A front nozzle plate 5 is secured, by screws 6, to the face of the back plate 2 and has a central opening with a wall 7 which defines a combustion chamber 8 around the flame-retention plate 9 of a mixer assembly of which the venturi plate 10 is mounted on the nozzle back plate 2 by axial locating pins 11 and screws 12 with axial spacers l3.

The venturi plate has an inner ring of venturi ports 14, in axial alignment with the air jets 3, and its rim forms the inner wall of an annular venturi passage 15 of which the outer wall is the wall 7 of the front nozzle plate 5.

The flame-retention plate 9 is secured to the venturi plate by a central screw 16 through a central boss 17 which abuts against the face of the venturi plate and provides the inner wall of an annular mixture chamber recess 18 in the plate 9 and bounded by a surrounding rim flange 19 with a small clearance from the venturi plate defining a peripheral outlet 20 for the gas/air mixture to the combustion chamber 8.

The mouth of the combustion chamber 8 has a cross sectional area and an axial profile determined by the size and shape of a lip flange 21 on the nozzle wall 7 and the contour of the rim 22 of the plate 9. This enables good flame retention to be achieved and thereby good burner control with a high turn down ratio with a single control through the pressure air supply pipe 23.

Gas supply, subject to a zero governor, is dependent upon and is thus regulated by flow through the venturi passages. To promote even radial flow of gas to the venturi passages, the back of the venturi plate is formed as a central conical deflector 24.

The main venturi passage 15, being formed by the radial clearance between the venturi plate 10 and the wall 7 of the front nozzle plate, can be determined simply by the diameter of the venturi plate.

It can be seen that the mixture assembly and nozzle plates are easily replaceable for selection to suit burner requirements and renewal in case of flame erosion or damage.

The invention is particularly useful for natural gas or other gases having a relatively slow flame speed and re quiring retention of flame for combustion in the region of issue of the gas to atmosphere.

We claim:

1. In a pressure-fed burner, a combustion chamber which is generally of annular configuration about a central axis and has a generally annular flame outlet opening therefrom in a generally axially direction, means for introducing into said combustion chamber a relatively major flow of a combustible gaseous mixture for generating a main flame, means for directing into said combustion chamber a relatively minor flow of a combustible gaseous mixture in a direction toward and generally normal to the direction of major flow therethrough, said minor flow being generally uniformly distributed about the entire periphery of said annular chamber.

2. A pressure-fed burner as claimed in claim 1 wherein said means for directing said relatively minor flow comprises a second chamber surrounded by said combustion chamber and communicating therewith through generally radially directed opening means extending generally uniformly about the radially inner annular surface of said combustion chamber.

3. A pressure-fed burner claimed in claim 2 wherein said opening means comprises a continuous slot in the annular surface between said second chamber and said combustion chamber.

4. A pressure-fed burner as claimed in claim 1 wherein said combustion chamber is defined by radially inner and outer annular sidewalls and an end wall disposed generally axially opposite said flame outlet opening, wherein said means for directing said relatively minor flow comprises a second chamber adjacent one of said sidewalls and communicating with said combus tion chamber through generally radially directed passage means extending generally uniformly about said one of said sidewalls, and wherein said means for introducing said major flow into said combustion chamber is located generally axially opposite said flame outlet opening and at least closely adjacent said end wall.

5. A pressure-fed burner as claimed in claim 4 wherein said second chamber is surrounded by said combustion chamber, and the passage means are formed in said radially inner wall.

6. A pressure-fed burner as claimed in claim 5 wherein said second chamber is defined at least in part by a first generally circular plate-like member, further comprising means supporting said first plate-like member such that outer peripheral portions thereof are spaced slightly from said end wall such that the clearance therebetween defines said passage means.

7. A pressure-fed burner as claimed in claim 6 wherein said end wall comprises part of a second generally circular plate-like member to one surface of which said first plate-like member is coupled such that said second chamber is defined between said two plate-like members, and the radially inner sidewall of the combustion chamber is defined by the outer peripheral portion of said first plate-like member.

8. A pressure-fed burner as claimed in claim 7 wherein the second plate-like member has its outer periphery spaced radially inwardly from an axially extended portion of the outer wall of said combustion chamber so as to define therebetween an annular passageway constituting said means for introducing said major flow into said combustion chamber.

9. A pressure-fed burner as claimed in claim 8 and further comprising means defining with the other surface of said second plate-like member a third chamber communicating with said annular passageway, said second plate-like member having openings therethrough communicating said third chamber with said second chamber, and means for supplying the components of a combustible gaseous mixture to said third chamber.

10. A pressure-fed burner as claimed in claim 9 wherein said means for supplying combustible components comprises jet passages, aligned with said annular passageway and said openings, for feeding an entraining gaseous component into said third chamber and thence into and through said annular passageway and said openings, and means for supplying a second gaseous component to the third chamber to be entrained by and mixed with said entraining gaseous component.

11. A pressure-fed burner as claimed in claim 10 wherein said jet passages are arranged in annular configurations.

12. In a pressure-fed burner as claimed in claim 1 comprising a main body member formed with a generally cylindrical hollow interior which is closed at one axial end and open at its other axial end, a removable assembly mounted in said hollow interior and dividing the interior into said combustion chamber and second and third chambers, said removable assembly comprising first and second plate-like members, said first platelike member being of lesser diameter than said second plate-like member and coupled to said second platelike member such that said first chamber is defined between said first and second plate-like members and said combustion chamber is defined by the outer periphery of said first plate-like member, a portion of the adjacent face of said second plate-like member, and a part of the interior surface of said main body member adjacent its open end, the third chamber being defined primarily between the other face of the second plate-like member and the closed end of said main body member, said closed end of said main body member including means for supplying to said third chamber the components of a combustible gaseous mixture, said second plate-like member including openings to communicate said second and third chambers, said means for introducing a relatively major flow to said combustion chamber comprising passage means communicating said third and combustion chambers and defined at least in part by said second plate-like member, said means for directing a relatively minor flow to said combustion chamber comprising flame retention passage means communicating said second and combustion chambers and defined at least in part by the outer peripheral portions of said first plate-like member adjacent said adjacent face of said second plate-like member so as to open into said combustion chamber relatively axially removed from said flame outlet opening. 

1. In a pressure-fed burner, a combustion chamber which is generally of annular configuration about a central axis and has a generally annular flame outlet opening therefrom in a generally axially direction, means for introducing into said combustion chamber a relatively major flow of a combustible gaseous mixture for generating a main flame, means for directing into said combustion chamber a relatively minor flow of a combustible gaseous mixture in a direction toward and generally normal to the direction of major flow therethrough, said minor flow being generally uniformly distributed about the entire periphery of said annular chamber.
 2. A pressure-fed burner as claimed in claim 1 wherein said means for directing said relatively minor flow comprises a second chamber surrounded by said combustion chamber and communicating therewith through generally radially directed opening means extending generally uniformly about tHe radially inner annular surface of said combustion chamber.
 3. A pressure-fed burner as claimed in claim 2 wherein said opening means comprises a continuous slot in the annular surface between said second chamber and said combustion chamber.
 4. A pressure-fed burner as claimed in claim 1 wherein said combustion chamber is defined by radially inner and outer annular sidewalls and an end wall disposed generally axially opposite said flame outlet opening, wherein said means for directing said relatively minor flow comprises a second chamber adjacent one of said sidewalls and communicating with said combustion chamber through generally radially directed passage means extending generally uniformly about said one of said sidewalls, and wherein said means for introducing said major flow into said combustion chamber is located generally axially opposite said flame outlet opening and at least closely adjacent said end wall.
 5. A pressure-fed burner as claimed in claim 4 wherein said second chamber is surrounded by said combustion chamber, and the passage means are formed in said radially inner wall.
 6. A pressure-fed burner as claimed in claim 5 wherein said second chamber is defined at least in part by a first generally circular plate-like member, further comprising means supporting said first plate-like member such that outer peripheral portions thereof are spaced slightly from said end wall such that the clearance therebetween defines said passage means.
 7. A pressure-fed burner as claimed in claim 6 wherein said end wall comprises part of a second generally circular plate-like member to one surface of which said first plate-like member is coupled such that said second chamber is defined between said two plate-like members, and the radially inner sidewall of the combustion chamber is defined by the outer peripheral portion of said first plate-like member.
 8. A pressure-fed burner as claimed in claim 7 wherein the second plate-like member has its outer periphery spaced radially inwardly from an axially extended portion of the outer wall of said combustion chamber so as to define therebetween an annular passageway constituting said means for introducing said major flow into said combustion chamber.
 9. A pressure-fed burner as claimed in claim 8 and further comprising means defining with the other surface of said second plate-like member a third chamber communicating with said annular passageway, said second plate-like member having openings therethrough communicating said third chamber with said second chamber, and means for supplying the components of a combustible gaseous mixture to said third chamber.
 10. A pressure-fed burner as claimed in claim 9 wherein said means for supplying combustible components comprises jet passages, aligned with said annular passageway and said openings, for feeding an entraining gaseous component into said third chamber and thence into and through said annular passageway and said openings, and means for supplying a second gaseous component to the third chamber to be entrained by and mixed with said entraining gaseous component.
 11. A pressure-fed burner as claimed in claim 10 wherein said jet passages are arranged in annular configurations.
 12. In a pressure-fed burner as claimed in claim 1 comprising a main body member formed with a generally cylindrical hollow interior which is closed at one axial end and open at its other axial end, a removable assembly mounted in said hollow interior and dividing the interior into said combustion chamber and second and third chambers, said removable assembly comprising first and second plate-like members, said first plate-like member being of lesser diameter than said second plate-like member and coupled to said second plate-like member such that said first chamber is defined between said first and second plate-like members and said combustion chamber is defined by the outer periphery of said first plate-like member, a portion of the adjacent face of said second plate-like membEr, and a part of the interior surface of said main body member adjacent its open end, the third chamber being defined primarily between the other face of the second plate-like member and the closed end of said main body member, said closed end of said main body member including means for supplying to said third chamber the components of a combustible gaseous mixture, said second plate-like member including openings to communicate said second and third chambers, said means for introducing a relatively major flow to said combustion chamber comprising passage means communicating said third and combustion chambers and defined at least in part by said second plate-like member, said means for directing a relatively minor flow to said combustion chamber comprising flame retention passage means communicating said second and combustion chambers and defined at least in part by the outer peripheral portions of said first plate-like member adjacent said adjacent face of said second plate-like member so as to open into said combustion chamber relatively axially removed from said flame outlet opening. 